The present study was carried out to evaluate subacute toxicity of a hydroethanolic extract of Solenostemon monostachyus (Esomo) in mice. Four groups of six mice were orally treated with Esomo at 0, 500, 1000 and 2000 mg /kg b.w. for 28 days and hematological, biochemical parameters and histopathological study carried out after experimental period. The control group of mice received saline solution.Subacute administration of Esomo did not exert any significant variation on body and organs weights, on food and water intake. This treatment did not show any change in hematological parameters such as erythrocytes and leukocytes count, hemoglobin concentration, hematocrit and mean corpuscular volume. Histopathological analysis and clinical blood chemistry parameters revealed no toxic effects of the extract. However, at doses of 1000 and 2000 mg/kg b.wEsomo induced thrombocytopenia. Our results exhibit that the extract of S. monostachyus is not devoid of toxicity.